The invention is more particularly concerned with a connection system having at least one terminal strip for cable terminations as used in distribution frames for telephone, business or domestic purposes. A terminal strip of this kind comprises at least one row of contacts connected in the usual way to the conductors of a cable and to jumper links. Document EP-0 138 824 shows terminal strips of this type, for example.
Terminal strips are usually juxtaposed along the length of a grounded metal mounting rail with their lateral faces close together or in contact.
If the bit rate of the data conveyed by the terminal strips is not too high, say up to 16 Mbit/s (megabits per second), there is no particular problem in using this arrangement. However, there is a demand for ever higher bit rates and it is thought that bit rates of around 155 Mbit/s will be achieved in data networks in the relatively near future. These bit rates entail electrical currents at high frequencies which, as they travel through unscreened conductors and the contacts of such terminal strips, generate electromagnetic interference that can disrupt the operation of nearby electrical and electronic equipment and especially nearby terminal strips, in particular terminal strips fixed to the same mounting rail, as these are the nearest.
A first technical problem is to avoid interference with nearby terminal strips fixed to the same rail, whose sides are near the terminal strip producing the interference, and to limit electromagnetic radiation in other directions from the terminal strip producing the interference.
French patent application FR-A-2 340 656 mentions the use of a screen inserted between modular units. The screen is connected to appropriate grounding points and its geometrical shape is similar to that of the units.
European patent application EP-A-0 489 642 discloses a terminal strip with snap-fastener lugs for attaching the terminal strip to a rail. The strip has two ground bars which run along each of its flanks and make electrical contact with the rail through lugs and whose ends are respectively connected to a ground terminal and a ground contact. The bars cover only a miniscule part of the terminal strip flanks and are locally visible or incorporated into the terminal strip.
The prior art solutions are extremely inadequate as they entail the use of an additional component (the screens) or they isolate the terminal strips only imperfectly (ground bars).